Isn’t this PSU a SMPS?.
Which isn’t good for audio due to the inherent noise they produce.
Martin
High-end switch mode power supplies are well filtered.
EMI (electromagnetic interference)
Is an electromagnetic disturbance from source to your equipment, which is the victim.
So it propagates from source to victim by means of conductive interference (power cables) radiated interference capacitive & inductive interference. A ferrite bead with a conductor through it is used forming a low pass filter to attenuate EMI.
Now( EMC ) comes into play Electromagnetic Compatibility. Which is defined by (IEC) Electrotechnical Commission; The ability of an equipment or system to function
satisfactorily in its electromagnetic environment without introducing intolerable electromagnetic
disturbances to anything in that environment.
When a piece of electronic equipment is supplied with an under voltage and or undercurrent source, it is more susceptible to EMI. . As the under current switch mode power supply source of the OP just demonstrated.